@AT:Application ofying
Principles of Evidence-Based Medicine to Occlusal Treatment for
Temporomandibular Disorders: Are There Lessons to Be Learned?
@AU:Heli Forssell, DDS, PhD
@AF:Senior Lecturer
@AF:Department of Oral Diseases/Pain
Clinic
@AF:
@AF:
@AU:Eija Kalso, MD, Ph.D
@AF:Associate Professor
@AF:Pain Clinic
@AF:Department of Anaesthesia
and Intensive Care Medicine
@AF:
@AF:
@AU:Correspondence to:
@AF:Dr Heli Forssell
@AF:Department of Oral Diseases/Pain
Clinic
@AF:Lemminkäisenkatu 2
@AF:Fin-20520
@AF:
@AF:Fax: +358-2-3338248
@AF:E-mail: heli.forssell@tyks.fi
@AB:Critical evaluation of treatment
methods has become an important part of health care,
and will certainly have a major influence on decisions about acceptable
treatment methods in the future. Evidence-based medicine (EBM) means the
systematic, explicit,
and judicious implementation of the best evidence in patient care. The most
reliable sources of evidence are high-quality systematic reviews and randomized
controlled trials (RCTs). A systematic EBM approach could be particularly
useful in the treatment of temporomandibular disorders (TMD), where
controversial and conflicting ideas about management are frequentcommon.
In this field, concerns about the lack of evidence are often expressed. This
article aims to elucidate and discuss the application of EBM to the treatment
of TMD,,
using the most controversial treatments, (ie,
occlusal treatments),
as an example. By applying the principles of EBM to TMD treatments,
we wish to highlight some of the important issues that form the basis for high-quality
care in this field.
A
systematic review of occlusal treatments (occlusal splints and occlusal
adjustment) updated to January 2003 revealed 16 RCTs ofn
occlusal splints, and 4 onf
occlusal adjustment. The overall quality of the trials was fairly low.
Recently, however, some high-quality RCTs ofn
occlusal splints have been published. The most obvious methodological
shortcomings in published trials included problems in defining the patient
population, inadequacies in performing randomization and blinding, problems in
defining the therapies or appropriate control treatments, short follow-ups, and
problems in monitoring patient compliance. Occlusal splint studies yielded
equivocal results. Even in the most studied area, stabilization splints for
myofascial face pain, the results do not justify definite conclusions about the
efficacy of splint therapy. Their clinical effectiveness to relieve pain also
seems modest when compared with pain treatment
methods in general. None of the occlusal adjustment
studies provided evidence supporting the use of this treatment method. The
clinical implications of the findings and future perspectives are discussed.
@CIT:J OROFAC PAIN 2004;18:XXX-;208;XXX.
@KW:<B>Key
words:<B> dentistry,
evidence-based medicine, occlusal
adjustment, occlusal splints, randomized
controlled trials, temporomandibular disorders
@TX1:The term
<I>Eevidence-based
medicine<I> (EBM) means refers
to the systematic, explicit,
and judicious use of best evidence in patient care. The In
practice, of EBM
means the integrationg
of individual clinical expertise with
the best available evidence, and moderateding
it by patient circumstances and preferences.<+>1,
2<+> The goal is obvious: EBM
aims to improve patient care. The efficacy and cost-effectiveness of health
services are also in the best interest of patients, as well as insurance
companies, governments, and others controlling payment
plans.<+>3<+>
@TX:Critical evaluation of treatment
methods has become an important part of health care,
and will certainly have a major influence on decisions about acceptable
treatment methods in the future. The positive effects of the practice
ofing EBM can already be seen in many
areas, such as in pain treatment in general.<+>4<+>
We believe that a systematic implementation of EBM could be particularly useful
in the field of temporomandibular disorders (TMD),
where a wide range of controversial and conflicting ideas concerning management
exists, and where concerns about lack of
evidence are frequently expressed.<+>
5-;208;7<+>
@TX:The present article aims to
elucidate and discuss the application of EBM in the most controversial treatment
methods of TMD,:
i .e. occlusal
treatments. By so doing so, we
hope to highlight some of the important issues bearing on improvements in the
scientific standards of the treatment of TMD.
@HA:About EBM
@TXA:The importance of developing an
evidence-based approach to clinical care and treatment is frequently emphasized
frequently.<+>8, 9<+> Traditionally, treatment plans in
clinical practice have been based on a mixture of knowledge gained through
training, practice traditions,
and subjective perception of clinical experiences. This can result in highly
varying treatments for the same condition, as well as ineffective, expensive,
and sometimes even harmful interventions.<+>3,
10<+> EBM aims to move beyond
anecdotal clinical experience by bridging the gap between research and the
practice of medicine and dentistry. The aim is to use an intervention that is
as accurate, as safe,
and as effectiveicacious
as possible.<+>11<+>
The most reliable sources of evidence are high-quality systematic reviews and
large randomized controlled trials (RCTs)
<+>4<+>
(Table Fig 1).
@HB:Why rRCandomized
controlled tTrials?
@TXA:Uncontrolled clinical studies and
case series can give preliminary evidence of the benefit of a treatment.
However, the extent to which patient outcomes reflect non-specific
effects, the natural history of thea
disease, or regression
to the mean, or specific effects of treatment is unclear in the absence of RCTs.<+>12-;208;14<+>
Non-specific or placebo effects, such as
physician attention and patient expectations, influence patients to report
improvement. Many pain conditions can have a
favorable natural history, and they may resolve on their own irrespective of
treatment. Patients with pain problems often have fluctuating symptoms, and
they seek treatment when symptoms are at their worst. The tendency of extreme
symptoms to return toward the individual’s more typical state is known as
the <I>regression to the mean.<I><+>12<+>
All these effects can be substantial,
and explain manyuch
of the benefits attributed to treatment.
@TX:The RCT has become the gold
standard for the assessment of treatment efficacy because of its potential
ability to control bias.<+>15<+>
Bias can be minimized by randomization, blinding, description of drop-outs,
and the use of appropriate control groups. Random allocation of treatments is
of crucial importance. If trials are not randomized, estimates of treatment
effect may be exaggerated by up to 40%.<+>16<+>
@TX:In practice, tThe
quality and validity of published RCTs can in practice show
considerabley
variation.<+>17<+>
Different types of quality and validity scales can be used to assess these.<+>18-;208;21<+>
Rigorous studies should be given more weight, whereas flawed RCTs do not
necessarily offer advantages over nonrandomized or cohort studies. Recently,
consolidated standards for reporting trials have been published in
order to improve the quality of reporting of RCTs.<+>22<+>
@HB:Why sSystematic
rReviews?
@TXA:Research evidence can be reviewed
by either informal or systematic approaches. The informal approach is used by
traditional narrative reviews. In these,
the reviewers do not follow formal strategies to identify, extract,
and summarize the research evidence.<+>19<+>
They can easily be biased,
and present a “personal estimate” of the evidence by the reviewer.<+>17<+>
Systematic reviews try to overcome the limitations of narrative reviews,
and be as objective and transparent as possible.<+>19<+>
For a systematic review to be scientifically sound, reviewers must clearly describe
the research question, the criteria for inclusion or exclusion of the primary
studies, the methods techniques to
assess the methodological quality of the studies included,
and the methods used to extract and synthesize the results of the primary
trials on which the conclusions are based.<+>23<+> It is often not possible or
sensible to combine (pool) data;,
this resultsing
in a qualitative rather than a quantitative
systematic review (meta-analysis).<+>17<+> Systematic reviews offer obvious
advantages over traditional reviews for the synthesis of the available
evidence.<+>19<+> However, oOne
of the greatest benefits of systematic reviews is, however,
the lessons they teach about trial methodology. They provide a means for quality
control over clinical trials,
and help clinicians to develop and apply better
research methodology and to produce more reliable evidence.<+>17<+>
@HB:EBM:
– oOne
pPart
of sScientific
wWork
@TXA:EBM should be seen as one part of
scientific work. Its foundation is in the knowledge achieved through
epidemiological studies,
and through basic science and experimental studies. This knowledge is used to
guide the questions asked in clinical patient care,
and tested in RCTs. The information ofbtained
through EBM can, on the other hand, feed basic science,
experimental, and epidemiological
studies (Fig 21).
@HB:EBM and pPain
tTreatment
@TXA:Due toBecause
of the subjective character of pain and the significant placebo
effect of pain treatments, the necedssity
to pay attention to trial design was emphasized much earlier in pain research
than in other areas of medicine. Until Up
to <B>[AU: Or “through”?]<B> 1994 there were more than
14,000 published RCTs ofin
pain relief.<+>4<+>
Most of these RCTs are about examined
the pharmacotherapy of acute and chronic pain, where rigorous
trial methodology is easiest to follow. Also, Mmany
other pain treatment methods have been tested in RCTs. In many cases, aAppropriate
controls and problems with blinding may in many cases make
these trials more challenging to perform.
@TX:Many statistical methods,
such as odds ratios and relative risk,
have been used to report the treatment
effects. The most “user-friendly” is NNT, or
the number- needed-
to- treat
(NNT). It tells how many patients need to be treated with a
particular treatment for 1 patient to achieve at least a 50% reduction in pain
beyond what would have been achieved with a placebo. The following formula is used to
calculate the NNT:
@TX:NNT = 1/(A<->improved<->/A<->total<->)-
;208; (C<->improved<->/C<->total<->)
@TXA:where A stands for active
treatment and C for control treatment (placebo). NNT can be used to compare the
relative effectiveness of different treatments across different studies,
given that the treatment effect has been measured with the same outcome
measures against the same comparator.<+>24<+>
@TX:Several meta-analyses have used
this criterion for a range of treatments in pain. According to these, the best
NNTs for at least 50% pain relief for analgesics in postoperative pain are
about 2. NNTs for antidepressants in
the treatment of neuropathic pain vary from 2.3 to 3.4.
In general, NNTs of 2 to 4 indicate that aeffective
treatment is effective.<+>24<+>
@HA:TMD: –A
Musculoskeletal Pain Conditions
@TXA:The term <I>temporomandibular
disorders<I> (TMD)
refers to a subclassification of musculoskeletal disorders affecting the
masticatory muscles and/or the temporomandibular joint (TMJ). The most common
presenting symptom is pain, which is usually aggravated by chewing or other jaw
functions.<+>6<+>
A Sseparationg
of masticatory muscle pain/disorders
from TMJ disorders is currently advocated. The most frequently used
classification subdivides TMD asinto
muscle (myofascial) pain, internal derangements of the joint, and degenerative
joint diseases.<+>25<+>
Even Although
the myalgia subtype is the most prevalent form, it is very usual for TMD
patients to receive a combinedation
diagnosis, with both muscle and joint problems.
Masticatory muscle pain seems to partly overlap with other pain conditions,
such as tension-type headache, neck pain,
and fibromyalgia.<+>26<+>
@TX:The etiology and the
pathophysiological mechanisms of TMD, like those of
other musculoskeletal pain problems, are so far poorly understood.<+>7,
27, 28<+>
Earlier etiological concepts based on a single factor,
e.g.,
prematurities in the occlusion, have lost scientific and clinical credibility.<+>27<+>
According to the prevailing multifactorial etiological
concept, there are many initiating, predisposing,
and perpetuating biomechanical, neuromuscular,
and psychosocial factors that are
involved.<+>27<+>
Intensive research on the pathophysiology underlying joint and muscle pain has
characterized the last decade of the TMD field. Understanding
of the mechanisms has increased,
along the with advances
in the understanding of the pain mechanisms in general.<+>29-;208;31<+>
Today, new treatment strategies are expected to arise from basic research
rather than from clarification of etiological
concepts.<+>28, 30,
32<+>
@TX:TMD are considered the most common
cause of non-dental pain in the orofacial region.
Theise
conditions affects
about 10% of women and 6% of men in any given year, giving a rough estimate of
450 million adults afflicted worldwide.<+>26<+>
Annually, 1% to-
3% of people seek professional help for the symptoms, thus making
TMD a significant health care problem.
@TX:Although athey
are prevalent disorders,
TMD seems to have a favorable course.<+>6,
33-;208;35<+>
Longitudinal epidemiological
findings indicate substantial fluctuation of symptoms and signs. Progression to
severe pain and dysfunction is very rare.<+>36<+>
A minority, usually less fewer than
20%, have either continued or increased pain.
@TX:Chronic TMD pain is similar to
many other common pain problems,
such as low back pain and headache,
in terms of levels of pain intensity and interference,
and psychological and psychosocial profiles.<+>37,
38<+> Psychological
factors are also seen as the most important risk -factors
ofor
chronicity.<+>26, 39<+> Along with this, comprehensive
diagnostic systems incorporating psychosocial, behavioral,
and physical components of the TMD problem have become widely accepted.<+>40,
41<+>
@HA:TMD cControversies
@TXA:Treatment goals for patients with
TMD include pain alleviation, decreased loading of the masticatory system, and
restored functions.<+>33<+>
The methods used to achieve these goals can be highly variable, such as patient
education and self-care, exercises, physical therapy, relaxation, biofeedback,
cognitive- behavioral
interventions, occlusal splints, occlusal adjustment, occlusal rehabilitation,
orthodontics, pharmacotherapy including intra-articular injections, and TMJ
surgery. All treatment approaches claim success, and the majority of the
patients are reported to improve.<+>33,
34<+> It is well recognized,
however, that we lack prospective studies using that
use appropriate outcome measures and controls to validate the
results.<+>6, 7,
42<+>
@TX:Different treatments and the
rationale behind them constitute one of the most controversial areas in the
field of TMD. Perhaps the most conflicting of these is the role of occlusal
factors.<+>6, 43-;208;47<+>
@TX:The interest in occlusal and other
structural factors was started by Costen’s hypothesis about the importance of
these as etiologic factors in TMD.<+>48<+>
Even ifAlthough
the original hypothesis was later refuted, the occlusal-structural model of TMD
causation has been extremely popular among dentists for decades. Along with the
belief that unfavorable occlusal contacts can lead to neuromuscular
disturbances and pain and dysfunction, occlusal treatments such as occlusal
adjustment of the natural dentition or occlusal splints were recommended,
and widely used.<+>44<+>
However, there is no universal agreement about which type of occlusal
interferences are considered detrimental to function,
or about the best way to perform occlusal adjustment.<+>43,
47<+> No consensus has been
reached about the design and occlusal scheme of the splints nor
about whether the mechanism of action
is related to occlusal or other factors.<+>34,
49, 50<+>
@TX:In recent years, the etiological
significance of occlusal factors has been increasingly questioned. Based on
epidemiologic data and systematic studies, the relationship between these and
TMD is considered weak or non-existent.<+>33,
34, 42, 47,
51, 52<+>
In line with this, the strategy of occlusal treatments has beencome
increasingly criticized.<+>34, 45,
53-;208;55<+>
In particular, the use of irreversible forms of occlusal treatments (such as
occlusal adjustment) has been discouraged in recent guidelines and textbooks on
TMD.<+>6, 33,
34, 56<+>
@TX:However, aAll
in the field do not, however, agree.<+>43,
46, 57, 58<+>
According to the argument most frequently presented
argument, the current empirical evidence is not sound enough to
justify the rejection of the hypothesis about the etiological
importance of occlusal factors because of methodological
problems in the studies.<+>43, 58<+>
Furthermore, Kirveskari et al<+>59<+>
showed in an RCT, in which
where young subjects underwent occlusal adjustment or mock
adjustment over a period of 4 years, that the elimination of the presumed
structural risk by real adjustment significantly decreased the incidence of
TMD. With these results, they suggested that the discussion
about occlusal factors and TMD should continue.
@TX:Despite the uncertainties in the
field of TMD, some general guidelines are offered for management today. It is
argued that TMD as a variant of musculoskeletal disorders should be considered
as a disorders
that, which can
be managed rather than cured.<+>7,
34, 56, 60<+>
Practice guidelines recommend reversible treatments, which should be tailored
to individual symptoms and patient characteristics.<+>6,
7, 33, 39,41<+>
A unifying consensus seems to prevail as regards one 1
important point in TMD therapy. Expert panels, new textbooks, and
new curricula for TMD education all emphasize that the treatments used should
be evidence-based.<+>3, 6,
11, 33, 53,
61<+> To avoid pure lip service
here, the next logical question is:,
wWhat
is evidence-based treatment of TMD?
@HA:TMD and EBMevidence-based
medicine
@TXA:The actual starting point for
discussion about TMD and evidence-based treatment was the report describing the
epidemiology of research for TMD by Antczcak-Bouckoms.<+>5<+>
It was performed to evaluate in broad terms the strength of evidence regarding
TMD therapy. In this systematic literature
search of literature published
betweenfrom
1980 toand
1992, more than 4,000 references to TMD were found. Of
these, about 1,200
regarded examined therapy.
Forty-one percent of the 1,200
references were classified as reviews,
and only about 15% were clinical studies. Less than 5% (n =
51) were RCTs. The findings indicated that virtually all the
evidence regarding therapy for TMD was likely to be subject to considerable
bias. Concerns about the state of
science in the field were expressed, and the importance tof
basinge
patient -care
decisions on evidence was emphasized. Later, the same concerns have
beenwere expressed by many experts in the
field.<+>14, 28,
44, 53, 62-;208;64<+>
@TX:Despite the great interest in EBM
and its possibilities to improve the treatment of TMD problems, systematic
searches for evidence have been rare. Only a few systematic reviews of TMD
treatments have been published.<+>65-;208;70<+>
In addition, in a recent systematic review of pharmacotherapy of facial pain,
studies concerning drugs used to treat TMD pain were also analyzed.<+>71<+>
The scarcity of systematic reviews at this point is somewhat surprising,
given the important role they are thought to have in trying to create a
comprehensive and unbiased picture about a particular clinical area.<+>19<+>
@HA:Systematic rReview
of RCTs onf oOcclusal
tTreatments
@TXA:In the field of TMD, the question
about evidence is especially intriguing when considering controversial, albeit widely
used, methods such as occlusal treatments. To find out whether studies are in
agreement with current clinical practices, we decided to conduct a systematic
review of all relevant RCTs onf
occlusal treatments for TMD symptoms.<+>67<+>
The review gave a qualitative overview about of
the evidence on these treatment methods. A quantitative review (i.e.,
systematic pooling of results) was not possible because of the heterogeneity of
the data. The research question, the search strategy to locate the studies, the
criteria for inclusion and exclusion of primary studies, the methods
techniques used to assess the
methodological quality of the studies included,
and the methods used to extract and synthesize the results of the primary
studies were carefully described in order to
allow critical appraisal.
@TX:The objective of our systematic
review was to evaluate the effectiveness of occlusal treatments (i.e.,
occlusal splints and occlusal adjustment) for the symptoms of TMD. A study was
included in the review if it was a randomized comparison of occlusal splint
therapy or occlusal adjustment with placebo, no-
treatment, or some other intervention used to treat TMD symptoms
in patients having who sought
treatment for these symptoms.
@TX:The search strategy for
identification of studies included different database searches (MEDLINEMedline,
EmbaseEMBASE,
Cochrane, DareDARE)
of literature published betweenfrom
1966 andto
March 1999. This was,
complemented by extensive hand searching.
@TX:Each trial was read independently
read by the authors of
our review and scored with the use of the quality scale presented
by Antczak et al,<+>18<+>
with minor modifications. The scale evaluates both the quality of the study
protocol, and the presentation and analysis of
the data. The scale assigns an arbitrarily defined set of weights to a list of
items, the presence and correctness of which are assumed to reflect the quality
of the research. If a study fulfills all the requirements, a score of 1.00 is
given. The specific items and weight given to each of them are presented in
Table 12.
@TX:In the review, a positive result
was defined as a statistically significant difference, as reported by the
authors, between occlusal splint therapy or /occlusal
adjustment and a control, in pain intensity, overall
success rating, or any other outcome measure used in the studies. Finally, we
reached consensus about the overall outcome of each trial and put emphasis on
the results of the latest follow-up.
@TX:Twenty-eight RCTs of occlusal
treatments were found. Eighteen studies met the inclusion criteria<+>72-;208;91<+>
(Table 32).
Fourteen of the RCTs were onexamined
splint therapy and 4 on examined occlusal
adjustment . One study compared occlusal splint
therapy to several types of control treatments.<+>73<+>
@TX:Based on simple vote counting, we
summarized that splint therapy was found to be superior
to 3 control treatments, and comparable to 12 control
treatments. Furthermore, splints were superior to a passive
control in 4 studies and comparable to it in another 4 (Table
23).
Occlusal adjustment was found to be equaivalent
to control treatment in 2 studies,
and inferior to control treatment in one1
study. It was equivalent
to a passive control in 1 study (Table 32).
@TX:On the basis of our analysis,
we concluded that RCTs seem to suggest that the use of occlusal splints may be
of some benefit in the treatment of TMD, but the evidence is scarce. On the
other hand, the few available studies do not provide evidence for the use of
occlusal adjustment.
@TX:To update the information of the
review, a literature search using the same search strategy as that in the
published review was undertaken to cover the time interval from March 1999 to
January 2003. The search provided 5 new RCTs ofn
occlusal treatments forin
TMD.<+>92-;208;96<+>
Kuttila et al<+> 94<+>
studied the efficacy of an occlusal splint in a non-patient
population with secondary otalgia and TMD, and therefore
the study did therefore not meet our inclusion
criteria. The trial by Minakuchi et al<+>
92<+> was excluded from further
analysis because patients were treated, in
addition to splint therapy, with other forms of therapy
in addition to splint therapy, which precluded the assessment of
the effects of occlusal splint therapy. The studies by Raphael and Marbach<+>93<+>
and Ekberg et al<+>96<+>
met our inclusion criteria and are included in the following evaluation (Table 23).
The study by Raphael at al<+>95<+>
was excluded, because it reported results of a group of patients,
which that was part of the material
presented in their earlier study.<+>93<+>
@TX:In the RCT by Raphael and Marbach,<+>93<+>
63 women meeting criteria for the myofascial subtype of TMD<+>25<+>
were assigned to use either a flat-plane, hard acrylic splint or a palatal
splint at night for 6 weeks. At the end of the study period, the groups were
compared for pain, number of painful muscles, functional complaints,
and psychological measures (mood and depression). The treatment groups differed
significantly after 6 weeks on only 1 of the 3 self-reported pain severity
measures. The authors concluded that active splints were of modest value for
patients with myofascial pain, but according to our estimate about the overall
outcome of the result of the trial, there were no significant differences
between the groups. Post hoc comparisons of study subjects with local versus.
widespread pain<+>93<+>
indicated that patients with local pain who received the active splint
experienced better more improvement
compared with than the other
patient groups.
@TX:In the study by Ekberg et al,<+>96<+>
60 patients suffering from myofascial pain were randomized to a stabilization
splint or a palatal splint group.
The study design was similar to their an
earlierprevious trial by the same
authors.<+>86<+>
After 10 weeks of treatment,
there were significant differences between the groups in favor of the use of stabilization
splintgroups
in for the
improvement of overall subjective symptoms, the prevalence of daily or constant
pain, as well asnd
the number of painful muscles. The overall result of the study was considered
positive.
@HA:Occlusal tTreatment
sStudies
and EBM rRules:
What mMakes
a gGood
RCT?
@TXA:As discussed earlier, the
methodological quality of the trial dictates the
credibility of the results. In the following, some of the most important
methodological aspects concerning the study protocol
of a good RCT will be discussed. We have assessed
these under the headings of the quality scoring system by Antczak et al<+>18<+>
(items marked with with an asteriskbold
letters in Table 12).
The evaluation is based on the RCTs analyzed in our review, and it is
complementsary to
the remarks in the discussion section of our systematic review.<+>67<+>
We focused particularly have
focused on what the lessons
that couldcan
be learned for future studies in this field.
@HB:Selection dDescription
@TXA:A detailed description of
criteria for inclusion and exclusion is the a
minimum requirement for an
RCT.<+>15<+>
Except for a few studies,<+> 77,81,91<+>
most RCTs provided this information. The actual definitions of the patient
samples varied, however. In 7 studies (including all studies ofn
occlusal adjustment), the material was described to consist of TMD (or alike)
patients, lumping together and patients
with muscle pain and different types of joint problems were placed
into a single group. However, tThe
distinct clinical entities that constitute TMDs
are, however, likely to exhibit
differences in treatment responses. Trials using more detailed case definitions
would probably be more sensitive,
and give more clinically useful information. The Research Diagnostic Criteria
for TMD (RDC/TMD) provide a systematic method of classifying the major subtypes
of TMD along a physical disease axis (Axis I) through a standardized clinical
examination.<+>25<+>
In addition, ithe RDC/TMDt
allows classification of the subject’s psychosocial
status (Axis II) based on standardized psychometric instruments and includes
self-reports of pain intensity and pain-related disability. So far, this instrument has
only been used in only one
1 RCT ofn
occlusal treatments.<+>93<+>
Its use in future trials would offer several advantages, including a common set
of methods and terms, and increased sensitivity to case
complex casesity.<+>7<+>
@TX:TMD patients can also differ
e.g. in terms of chronicity of their TMD pain, differing psychological
characteristics, and the presence or absence of widespread pain or concomitant
bruxism. Possible differences in treatment responses based on these
distinctions have so far not been tested in RCTs on occlusal treatments,
except for spread of pain and severity of bruxism in the most recent trial.<+>93,
95<+> Given the differing
pathophysiological mechanisms of acute and chronic
pain, pain duration should receive more attention in future trials.
@HB:Definition of tTherapeutic
rRegimen
@TXA:The description of therapeutic
procedures must be sufficiently detailed to allow comparison with other
studies. This was usually accomplished in the RCTs ofn
occlusal splints. In most studies, a flat-plane,
hard acrylic splint adjusted to even out
occlusal contacts and with provide canine
guidance was used. The issue seems to be much more complicated for occlusal
adjustment procedures. The procedures performed varied from elimination of
gross interferences to meticulous occlusal equilibration procedures consisting
of four 60- minute
treatment sessions.<+>87, 88<+>
Experts should agree about the way to perform the procedure so
that credible RCTs on the subject may be instituted.<+>43,
55<+>
@TX:Selection of the control treatment
or condition is a complicated matter,<+>62,
97<+> and ideal ways to handle
this, in especially
in splint studies,
haves
perhaps not yet been established.<+>62<+>
Waiting list controls are used in some studies, but they do not rule out the
placebo effect, and can in fact include negative
effects while reducing the expectation-fulfillment contamination.<+>62,
97, 98<+>
The use of a placebo control group can balance the nonspecific effects in the
treatment group, and allow for independent assessment
of the real treatment effect. The use of the palatal (non-occluding)
splint as a placebo condition in splint studies<+>99<+>
can, however, contain result in unintended
active treatment components, e.g.,
by increasing cognitive awareness of oral habits<+>
49, 50<+>
or changing muscle function.<+>100<+>
They can thus overcontrol for the active ingredient of the
stabilization splint therapy.<+>14,
62, 63<+>
@TX:An obvious problem with the
use of active control treatments used in
RCTs ofn
occlusal treatments is that the efficacy of most of them is not known. While many
RCTs indicated that occlusal splints were as effective as the control
treatment, it remains unclear ifwhether
treatments were indistinguishable from each other because they were equally
effective or because they were equally ineffective.
For the time being, only placebo controls or inactive (waiting list) controls
are justified.
@HB:Follow-up sSchedule
@TXA:Trials should be sensitive for
the long-term outcomes. This was demonstrated clearly in our systematic review,
where studies with longer follow-ups generally did
generally not show favorable treatment
results, despite good short-term results in
some of them.<+>82, 89,
90<+>
@HB:Test of aAdherence
to tTreatment
@TXA:Future splint studies should pay
attention to monitoring patient compliance with given instructions about splint
use. In the published studies, this was assessed only
seldom assessed.<+>82,
83, 93<+> The same applies to the use of
concomitant treatments. Only 3 RCTs clearly stated that no other pain
treatments were allowed or performed during the trials,<+>83,
84, 86<+>
or that the study groups did not differ on the use of cointerventions.<+>93<+>
Two RCTs did not report on drop-outs
or loss to follow-up.<+>73, 77<+>
The number of drop-outs in the RCTs was usually less
fewer than 10%, which is considered
acceptable.<+>18<+>
Systematic reporting of protocol violations in RCTCs
allows more precise estimates of bias and of the
generalizability of the findings.<+>101<+>
@HB:Randomization
@TXA:Detailed instructions about
acceptable ways to perform a randomization
are provided described in
several textbooks.<+>8, 15<+>
Randomization should be concealed so that it eliminates any influence of the
investigators on the allocation of the interventions. Properly performed
randomization is considered crucially important in trial design.<+>102<+>
Trials that use inadequate or unclear allocation concealment tend to
overestimate the effect of treatment,
and can yield up to 40% larger estimates of effect in comparisoned
to studies that useing
adequate allocation concealment.<+>16<+>
It was Ssurprisingly,
that the procedure of randomization
was described in only 2 studies.<+>86,
96<+>
@TX:Although randomization eliminates
systematic bias, it does not necessarily produce perfectly balanced study
groups with respect to prognostic factors. This was the case in 3 studies,
where random assignment had failed to equate the study groups on
with respect to pretreatment symptoms.<+>75,
79, 91<+>
The unbalanced randomization was not taken into consideration in 2 of them during
the analysis of data.<+>75, 91<+>
Further more, 3 studies did not report the results
of randomization results.<+>73,
77, 81<+>
@HB:Blinding
@TXA:Nine RCTs used blinding (single-
or double-blind procedures), and the
rest were open studies. Unfortunately, the fulfillment of the blinding
procedures was not mentioned in any of the studies. Open trials always involve
a risk of bias. This is a concern,s
especially in studies that useing
subjective outcomesmeasurements,
such as pain scores, as outcome measures.<+>4,
103<+> Double-blinding may not
always be possible, but there should never be objections in to
keeping blinding the
investigator who assessesing
the treatment results blind.<+>15,
103<+> However, tThe
importance of blinding as a source of bias is considered, however,
somewhat less important than that of adequate allocation concealment. The lack
of double -blinding
is reported to overestimate the treatment
effects by roughly 17%.<+>16<+>
@HB:Prior eEstimate
of sSample
sSize
@TXA:The number of patients per study
group was less than 15 in 7 of the RCTs. Reliable findings are considered
unlikely infrom
trials with inadequate group sizes.<+>104<+>
Large enough gGroup
sizes that are large enough to produce
statistical significance should be chosen through power calculations. For pain
studies, the usual size is 30-
to 40 patients for a 30% difference between active treatment and
placebo to become apparent.<+>4<+>
Power and sample size calculations for clinical trials of
myofascial pain of the jaw muscles are described by Dao et al.<+>105<+>
@TX:While the size of the sample
population depends in parte.g.
on the outcome measures of the study,<+>60<+> the primary outcome measure
should nevertheless be chosen at this
pointhe outset of the study. <B>[AU:
Please clarify this sentenceSentence
correct as edited?.]<B>
Furthermore, the determination of the primary outcome measure pre hoc is in
general considered an important part of good trial methodology.<+>22<+>
So far the methods to measure treatment success have varied, and for many
outcomes used, there is no evidence about their reliability and validity.<+>60,
106<+> The use of standardized
outcome measures and reporting of data would enable pooling and comparison of
different studies.
@TX:Most of the RCTs published after
1990 have used visual analog scales (VAS)
to measure pain. VAS pain scales are
in general widely used in all types of pain studies,<+>4<+>
and have been shown to be a valid tool.<+>107<+>
As a general rule, it is required that treatments improve outcomes that are
important to patients.<+>108<+>
The use of pain relief as the primary outcome measure in trials on TMD
treatment ismakes
sensible, asince
pain is the cardinal symptom of TMD,
and the main reason to seek treatment.<+>105,
109<+> Secondary outcomes should also
take into account the multidimensional nature of TMD as a pain problem, and
cost-effectiveness of the methods should be evaluated. Possible adverse effects
connected with occlusal treatments have so far received onlvery
little attention.<+>76, 84,
85, 88<+>
All these outcomes are essential for clinicians
and patients ftor
make informed treatment decisions where the probability of benefit
is weighted against the costs
and possible adverse effects.
@HA:Is tThere
eEvidence
of eEfficacy
for oOcclusal
tTreatments?
@TXA:The process of drawing
conclusions about the efficacy of a particular treatment on the basis of the
results of a qualitative systematic review is not an
easy task. As described earlier, simple
vote counting of the results of the RCTs ofn
occlusal splints and that were included
in our systematic review yielded equivocal findings, and we were not able to
draw firm conclusions. On the basis of our analysis, however,
we did, however, suggest that the use of
occlusal splints might be beneficial. Unfortunately, the results of the 2 newest
studies could not give the final answer on the efficacy of splint therapy. In
the following, the process of analyzing the results that leading
us to these conclusions is described in more detail.
@TX:A simple vote-counting procedure,
in which the amount number of
negative studies versus the number of positive studies is
counted, takes no accountignores the
possibility that how valid
this estimate may be invalid
might be, e.g.,
qualitatively weak studies are may
be given the same weight as high-qualitygood
studies. Previous studies have indicated that trials with lower quality may be
more likely to report positive results.<+>17<+>
Thus, the quality scores can be of
assistance when drawing conclusions. No such trend, however, was found
concerning studies included in our systematic review.
@TX:Obviously, studies with
adequate/good quality should be given more weight.<+>17<+>
If an arbitrary cut off
point of 0.50 for the quality score<+>18<+>
is used, it we are leftleaves
us with 5five
stabilization splint studies<+>
75, 83, 86,
93, 96<+>
and 1one
soft splint study.<+>85<+>
The outcomes of the stabilization splint studies indicated that stabilization
splint therapy is either statistically
superior to palatal splint therapy<+>
86, 96<+>
or that it is equivalent
to palatal splint therapy.<+>75,
83, 93<+>
The methodologically strongest studies ended came
toin different conclusions.<+>
83, 86, 96<+>
These studies differed from each other in the use of outcome measures and the
analysis of the results. Dao et al<+>83<+>
presented continuous data on pain intensity and unpleasantness and quality of
life. The overall pattern of group differences was analyzed from baseline
through the eight 8 weeks
of follow-up to assess the effects of the
treatment over time and
treatment effects. This type of measurement best
reflects best the true changes in symptoms.
Ekberg et al<+> 86,
96<+> used a different set
of different outcomes, and in statistical
testing, time-by-time comparisons of
dichotomous variables at baseline and end of the study were made. Some of the
comparisons yielded statistically significant differences between the study
groups.
@TX:In 4four
of these RCTCs
the patients suffered mainly from a myofascial
type of TMD pain,<+>
75, 83, 93,
96<+> and in one1
study the patients suffered mainly from
joint pain.<+>86<+>
Thus we conclude that even in the most studied area, ;209;stabilization
splint therapy for myofascial face pain;209;,
the results do not justify definitive conclusions about the
efficacy of this therapy.
@TX:So far, we have discussed the
statistical efficacy of splint therapy. What could be the clinical
importance of the results presented? We can try to estimate this in several
ways. First, a closer look at the changes in pain intensity over time in the
studies by Dao et al<+> 83<+>
and Raphael and Marbach<+> 93<+>
indicate that the actual differences between in
VAS pain intensities between stabilization splints
and palatal splints were marginal;209;,
being about 1one
or less on a 10-
unit scale or less. In pain-
treatment studies, the NNT values areis
often used to give an impression about the clinical efficacy of the treatment
methods, as described earlier. Unfortunately,
most of the RCTs on occlusal splints did not provide data that made the
calculation of these values possible. To give an example of the use of
NNTs in TMD splint studies, the
NNTs for 50% reduction of worst pain with
stabilization splint versus palatal splint wasere
calculated for the studies by Ekberg et al,<+>
86, 96<+>
who reporteding
the most positive outcomes among the high-quality studies. The calculated NNT
values were 6 for TMD patients suffering from joint pain<+>
86<+> and 4.3 for patients with TMD of
mainly myogenous origin.<+>96<+>
Thus, about 4- to 6
patients are needed for 1one
more patient to receive a 50% reduction in worst pain with a stabilization
splint compared to a palatal splint. Thus, cCompared
with pain treatment methods in general, the therapeutic value of splints seems thus
only modest, and the differences between stabilization splints
and palatal splints seem not to
be clinically unimportant. The possibility that
palatal splints pose active treatment ingredients,
as discussed earlier, needs to be taken into account here.
It might be interesting to note that the best NNT valuess
for more than 50% pain relief in TMD for drugs versus placebo were calculated
to be 2.7 and 3.5.<+>71<+>
@TX:None of the 4 RCTs onf
occlusal adjustment provided evidence for the use of this treatment method. The
performed RCTs were mainly of low quality, and only the study by Vallon et al<+>
89, 90<+>
had a quality score over 0.50. In that study,
occlusal adjustment was compared to passive control (counseling only). Despite
some short-term benefits, occlusal adjustment had little or no effect in the
long-term perspective.
@HA:Clinical iImplications
and fFuture
pPerspectives
@TXA:Does the widespread
use of oral splints need to be re-evaluated because of the lack of clear evidence
of their efficacy? The same question has been presented in other critical
reviews about splint therapy, but the answers have varied. Marbach and Raphael<+>
63<+> suggested that appliances
should not be recommended for musculoskeletal facial pain because of no
a lack of evidence of their long-term
efficacy. Dao and Lavigne<+>
50<+> and Feine et al<+>
60<+> had another view. Their
arguments were based on a further analysis of the results of the RCT by Dao et
al,<+> 83<+>
where additional data of perceived pain relief were added to compare these to
true pain relief (efficacy).<+>60<+>
Patients who had worn either the stabilization splint or palatal splint
reported significantly more pain relief than those in the passive control
group. Because of the data to support the effectiveness, though not the
efficacy, of oral splints they recommended that splints can be used as an
adjunct to pain management. Although final answers to the question about the
efficacy of splint therapy cannot be given at the moment, the latest studies
have provided some further support ftor
their use. The recommendation may still remain valid until the question is
solved through new high- quality
RCTCs,
or until evidence for other more
effective and less costly therapies hasve
appeared, as also suggested by Raphael et al.<+>95<+>
@TX:Since there is no evidence for the
efficacy of occlusal adjustment in TMD, its use cannot be recommended. This
conclusion is in line with that made in the recent reviews by Koh and Robinson<+>
70<+> and Tsukiyama et al<+>,55<+>
and follows the recommendations made by several experts in the field.<+>6,
33, 34, 56<+>
The small number and the poor quality of most of the published RCTs do not,
however, allow definite conclusions,
because lack of evidence cannot be interpreted as evidence of lack of effect.
If the principles of EBM are to be followed, good-quality RCTs are necessary to
provide the answers and to solve the discrepancy in opinions.
@TX:We have focused here on the
occlusal methods among the many TMD treatments
for TMD. On the whole, compared to the impression gained through
uncontrolled studies that reporteding
high success rates, the role of occlusal treatments as a treatment of choice
for TMD problems changes radically when it is evaluated critically with the
rules of EBM. It is clear that more research is needed before their final role
in the treatment of TMD can be solvedunderstood.
@TX:The principles of evidence and the
rules about how to perform a good RCT are
the same for all methods of treatment of TMD, and obviously all of them should
be assessed with the same rigor as occlusal treatments. All relevant treatment
methods should be assessed and tested, including all those which that
are widely used today. Effort should also be focused on pharmacotherapy,
which is an underinvestigated area within the TMD
field.
@TX:We firmly believe that acceptance
of criteria for evidence-based clinical practices and a strong emphasis on
performance ofing
RCTs with good trial methodology would help to clarify many uncertainties and
controversial issues in the TMD field, as as
it has been done in many other areas of
medicine. It would be exciting to consider the consequences of reversing the
ratio between published review articles and original RCTs on the treatment of
TMD during the next decade.<+>5<+>
One can only speculate what difference it would make for in
our understanding about the high-quality care of TMD patients. However,
EBM alone does will not,
however, change the world. Innovative basic science, experimental
clinical studies, and epidemiological
studies form the basis ftoor
the practice of EBM. The high standard of science in many areas of TMD studies
should encourage all those who are working in the field to
use the potential of EBM to move TMD treatment toon
a new level of scientific rigor.
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@FL:<B>Fig 1<B>
Type and strength of efficacy evidence (McQuay and Moore<+>4<+>).
@FL:<B>Fig 12.<B>
Algorithm onshowing
how different methods of research complement each other.
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> results significantly better than
= results comparable to
< results significantly worse than
Control treatment=any active control treatment
Passive control=control group without any treatment
or waiting list control or stabilization splint used only 4X30 minutes (Dao et
al 1994)
BL, baseline; CG, control group; WL, waiting list
control; TENS, transcutaneous electrical nerve stimulation; Pain VAS, pain
visual analogue scale
@AT:Critical
cCommentary
1: Application ofying
Principles of Evidence-Based Medicine to Occlusal Treatments for
Temporomandibular Disorders: Are There Lessons to Be Learned?
@AU:Dr. Glenn
Clark,
@AF:Professor
@AF:Oral
Biology and Medicine
@AF:
@AF:
@AF:
@AF:Fax:
+310-206-5539
@AF:E-mail:
glennc@dent.ucla.edu
@TX1:The focus article<+>1<+>
performs an admirable review of the literature on occlusal-based treatments for
temporomandibular disorders (TMD).
The noteworthy accomplishments
of this article areis
that the method by which used by the
authors to selected
only high-quality articles for review was fully described, logical,
and appropriate. Specifically,
they were looking for evidence-based articles that had reasonable quality with
regard to experimental design and objective research outcomes. Another
noteworthy feature is that the authors also
included good descriptions of the
how some of the control therapies, which are usually presumed to be non-active
therapies, might be able to produce an active therapeutic result. For example,
they noted that palatal splints have been used as a control or non-active
treatment, but this method may instead be an active device that is fully able
to influence and reduce jaw muscle hyperactivity. The final positive comment is
that these authors appropriately discussed the limitations of any research
study where in which subjects
are not randomly assigned to a treatment procedure. The authors pointed out
that most prior studies claiming randomization have not adequately described
the methods used. Inadequate randomization may result in inequality and
heterogeneity of the treatment groups not being equal
and homogeneous. They also appropriately pointed out that one
a potential confounding factor in the
attempt to find a suitable treatment approach will be etiology of the disease.
They noted that, unfortunately, TMD is
are not categorized by etiology,
and thiswhich is a
substantial limitation is a
substantial limitation. Moreover, current diagnostic systems,
which depend on signs and symptoms and joint imaging, do not identify etiology.
@TX:The critical points about this
review are that the authors did not explain fully why they suggested that patients
with muscle problems patients
should be separated from those with
temporomandibularTM
joint (TMJ) problems patients in
future treatment research. While this
recommendation has good face validity, it is not clear that making this
distinction is so easily accomplished made.
For example, if all TM TMJ joint
clicking patients,
who have a predominantely
musculear
pain disorder and just happen to have joint noises are to be excluded, this
specification process might eliminate a large portion of the population.
Another example is that most muscle pain patients also have joint tenderness;
and again, this
again would make the specification
process intrusive and highly exclusive. While this dilemma is solved by simply
including all patients and then sorting them out
afterwards, to see if any cluster of symptoms
is unduely effected by the therapy being
tested, the problem here is that you then need a
calibrated examination which must beis
performed blind to subject (control,
versus patient) and treatment time (before/
during/ or after)
status.
@TX:A second critical issue that
is identified is the authors’ conclusion
regarding the efficacy of occlusal treatment for TMD. While I agree and believe
the literature strongly supports the concept that occlusal adjustment is not a
logical therapeutic approach for chronic, spontaneous-
onset TMD problems, this conclusion is not so
clear for occlusal appliance therapy and TMD symptoms. Certainly occlusal
appliances have their limitations as an intervention, but the issue comes down
to how are occlusal appliances arebeing
used. If they are expected to serve as a cure
for TMD, then the data suggests
they have a weak efficacy at best. If,
however, they are being used as a management method to
protect teeth that are sore or worn, or to make a patient more aware of a
destructive behavior, they have a clearcut
merit. In general, in considering the treatment efficacy of occlusal
appliances, the discussion can be divided into 2 components: <I>(1)<I>
aAre
occlusal appliances a cure for the TMD problem?
and <I>(2)<I>
aAre
occlusal appliances a reasonable method of providing help and protection for
some selective TMD patients.?
The authors did not address this distinction, and this is largely because prior
research has not examined the utility of these devices as a therapeutic aid. A logical conclusion to reach for
the efficacy of occlusal appliances would be that “as
a bite guard that prevents abnormal tooth attrition and/or reduces individual
tooth loading, and sometimes changes clenching behaviors, these devices have
merit.”.
It would be illogical to suggest that
these devices stop a strong, long-term sleep bruxism behavior, that they put a
loose temporomandibular joint (TMJ)
disc back in place, or that they resolve arthritic
destruction of the TMJ.
@HA:References
@REF:1. Forssell H, Kalso E. Application
ofying principles of evidence-based
medicine to occlusal treatments for temporomandibular disorders: Are there
lessons to be learned? J Orofac Pain 2004;18:xxx;208;-xxx.
@AT:Critical Commentary 2: Application
ofying Principles of Evidence-Based
Medicine to Occlusal Treatments for Temporomandibular Disorders: Are There
Lessons to Be Learned?
@AU:Iven Klineberg
@AF: